On the west steps, three markers show differing mile high elevation calculations.
2003 - Bottom - step 13 - NAVD 1988 - Metro State College
1909 - Milddle - step 15 - carved in 1947 - University of Denver
1969 - Top - step 18 - NGVD 1929 - Colorado State University
The earth has not moved that much in the last 100 years. The changes are due to more accurate surveying grids, and revised sea level datums.